熵调控的Gd_(2)Co_(17)金属间化合物的结构与室温磁性能  

Structures and room-temperature magnetic properties of entropy-modulated Gd_(2)Co_(17) based intermetallic compounds

作　　者：董霄鹏 赵兴 殷林瀚 彭思琦 王京南 郭永权[1] Dong Xiao-Peng;Zhao Xing;Yin Lin-Han;Peng Si-Qi;Wang Jing-Nan;Guo Yong-Quan(School of Energy Power and Mechanical Engineering,North China Electric Power University,Beijing 102206,China)

机构地区：[1]华北电力大学能源动力与机械工程学院,北京102206

出　　处：《物理学报》2023年第10期290-301,共12页Acta Physica Sinica

摘　　要：熵调控材料因其独特的设计理念和优于传统合金的性能而受到广泛关注.本文将熵调控的设计理念引入金属间化合物中,设计并通过真空电弧熔炼的方法制备了一系列熵调控的Gd_(2)Co_(17)金属间化合物,期望通过熵调控的方法来稳定其结构,改善其磁性能.应用热力学理论预言熵调控的Gd_(2)Co_(17)系列金属间化合物具有稳定的单相,其单相性被X射线衍射实验所证实.通过组态熵调控原子尺寸因素,获得了菱方和六方两种晶体结构.熵调控改善了Gd_(2)Co_(17)系列金属间化合物的室温磁性能,过渡族金属位的熵调控使磁各向异性发生由基面到易轴的转变,稀土位的熵调控有助于提高其矫顽力,所有熵调控样品室温时的饱和磁矩均比二元Gd_(2)Co_(17)显著提升,可能是稀土或过渡族金属子晶格磁矩无序取向削弱了金属间化合物中稀土的4f电子与过渡族金属的3d电子磁矩之间的反平行交换作用所导致.磁价模型研究表明:熵调控设计导致Gd_(2)Co_(17)系列金属间化合物中Nsp↑(未极化sp导带中的电子数目)增加,增加了导带电子作为媒介引发过渡族金属子晶格的3d电子与稀土的4f电子之间强磁交换作用的概率,形成以游动的s电子为媒介,使磁性原子中局域的4f电子自旋与其近邻磁性原子的3d电子自旋产生交换作用,进而表现出饱和磁矩增大.本研究有助于提高熵调控的Gd_(2)Co_(17)的潜在应用性.The entropy-modulated material has been a hot topic due to its unique design concept and excellent properties.However,previous studies of entropy-modulated materials mainly focused on the alloys with simple face-centered cubic,or body-centered cubic,or hexagonal close-packed structures.In this work,the design concept of entropy-modulation is introduced into Gd_(2)Co_(17) based intermetallic compound,and the effect of high configuration entropy on the structural stabilization and room-temperature magnetic properties of Gd_(2)Co_(17) based intermetallic compound are studied systematically.The samples are prepared by vacuum Arc melting technology in an ultrahigh-purity Ar atmosphere and followed by annealing at 1000℃for 8 days and finally by quenching in cool water.The fine powders are prepared by grinding the ingots in an agate mortar.The powder XRD and SEM-EDS are used to check the crystal structures and chemical compositions.To study the magnetic properties,the column-like samples are prepared by mixing the fine powder and epoxy with a weight ratio of 1∶1,and then aligned under an applied field of 1 T at room temperature.ΔHmix N"sp The high configuration entropy is found to play an important role in the structural stabilization and magnetic properties of Gd_(2)Co_(17) based medium-and high-entropy intermetallic compounds.The XRD patterns and Rietveld structural refinement results confirm that all the samples are single-phase.The structure depends on the effective atomic radius RA,the structure of entropized Gd_(2)Co_(17) based intermetallics can be stabilized into rhombohedral Th2Zn17-type with RA>1.416 or hexagonal Th2Ni17-type with RA<1.4105.According to thermodynamic calculations of entropized Gd_(2)Co_(17) intermeatllics,the atomic radius difference Dr ranges from 0.55%to 1.81%,and the mixing enthalpy is corresponding to 0 for the rare earth site,–4 to–1 kJ/mol for the transition metal site,and–8.54 to–5.13 kJ/mol between rare earth and transition metal sites.It is suggested that all the thermody

关 键 词：Gd_(2)Co_(17) 高熵金属间化合物 RIETVELD结构精修 磁价模型 

分 类 号：TG111[金属学及工艺—物理冶金]